What's more, I'm more than happy to use my skills and equipment to equip and train neighbors in the event it were necessary. I have lots of guns and ammo because I enjoy them, not because I see them as magical talismans or because I intend to use them against the innocent during civil unrest.
The stereotype of a slightly-unhinged and heavily-armed prepper is just that - a stereotype. In truth most people who the general public would call "preppers" are like me; I have enough "stuff" to get my family through reasonable hard times and the rest of my capital is spent trying to build a foundation for retirement.
One family like mine in a small community with a few other families all pitching in, given basic training and loaned arms would be handily deter the opportunistic during a Katrina-scale "event".